1. Field of the Invention
This invention relates to an insoluble, hydrolysis resistant polymer foam support onto which microorganisms can be bound.
2. Description of Previously Published and Related Art
It is known to produce aspartic acid by the action of microorganisms which enzymatically convert ammonium fumarate to aspartic acid, and to bind the microorganisms to a porous foamed polyurethane substrate. See U.S. patent application Ser. No. 187,938 filed Sept. 17, 1980, now abandoned, and the article "Immobilization of Escherichia coli Cells Containing Aspartase Activity with Polyurethane and Its Application for L-Aspartic Acid Production" by M. C. Fusee et al in Applied and Environmental Microbiology, Vol. 42, No. 4 (October 1981) pg. 672-676. However, the polyurethanes used in the process described in the article were derived from the toluenediisocyanates (TDI) and, therefore, contained urethane linkages which were susceptible to alkaline hydrolysis in the strongly alkaline reaction medium. After about 2 weeks the hydrolysis can cause collapse of the foam support bed.
3. Objects of the Invention
It is an object of this invention to obtain a range of hydrolysis resistant polyurethane polymer foams which can be used to support microorganisms.
It is a further object of this invention to produce L-aspartic acid under high pH conditions with microorganisms bound to a series of hydrolysis resistant polyurethane polymer foams.
These and further objects will become apparent as the description of the invention proceeds.